Making Better Measurements

Agilent

4 Steps for Making Better Power Measurements

Application Note 64-4D

2

Four Steps for

Making Better Power

Measurements

Before you select a power meter and

its associated sensors, make sure

that you have taken the following four

steps, each of which can infl uence

the accuracy, economy, and technical

match to your application.

1. Understand the characteristics of

your signal under test and how

they interact with the power-

sensing processes.

2. Understand power measurement

uncertainties and traceability

to a primary power standard at

a national laboratory, such as

the U.S. National Institute of

Standards and Technology (NIST).

3. Understand the characteristics

and performance of available

sensor technologies and operating

features of various power meters.

4. Make the performance

comparison and select the right

product for your application.

Even a cursory analysis will reveal that

present power sensor technologies’

have considerable overlap in

capabilities. New system technologies,

such as wireless modulation formats

and their associated production

test requirements, will often require

some combined measurements such

as time-gated peak parameters or

computed data such as peak-to-

average ratios. And you can be sure

that all that data will be required at

speeds that push the state of the art.

Your analysis might also include

considerations of the installed base

of other sensors and power meters in

your organization’s inventory. And, it

should consider the traceability chain

of your organization’s metrology lab to

national standards.

This application note will provide you

with a brief review of the four factors

that infl uence the quality of your

power measurements. It will also offer

other suggested information sources

with more technical details, such as

Agilent Application Note, AN 64-1C,

“Fundamentals of RF and Microwave

Power Measurements”, publication

number 5965-6630E.

Power: The Fundamental

RF and Microwave

Measurement

Power measurement is the

fundamental parameter for

characterizing components and

systems at RF and microwave

frequencies. Above the range of

30 MHz to 100 MHz, where the

parameters of voltage and current

become inconvenient or more diffi cult

to measure, microwave power

becomes the parameter of choice.

Power specifi cations are often the

critical factor in the design, and

ultimately the performance, of almost

all RF and microwave equipment.

Power specifi cations are also

central to the economic concept of

equity in trade. This simply means

that when a customer purchases a

transmission product with specifi ed

power performance at a negotiated

price, the delivered product must meet

that specifi ed power when installed

and qualifi ed at a distant location,

perhaps in another country. Accuracy

and traceability of your power

instrumentation will help ensure this

measurement consistency.

3

STEP 1

Understanding Your Signal

Under Test

A world of signal formats

System technology trends in modern

communications, radar, and navigation

signals have resulted in dramatically

different modulation formats, some of

which have become highly complex.

The objective of this section is to

briefl y examine a range of typical

formats to see how their spectrum

characteristics interact with various

power sensor technologies.

Wireless and cellular systems depend

on digital I-Q (inphase-quadrature)

modulations at high data rates and

other spread-spectrum formats.

Because the fi nal transmitted signal

combines multiple carriers, statistical

processes at work that can create

extremely high peak power spikes,

based on a concept called crest factor,

described in the following paragraphs

and in the section entitled “Digital and

complex formats.”

Wireless systems also contain

frequency-agile local oscillators which

“hand-off” the vehicle’s signal as it

moves from ground cell to ground cell

and links up to each new base-station

frequency. Sometimes the power

perturbations, which occur during

the frequency transition, need to be

characterized.

Some radar and EW (counter-

measures) transmitters have the

traditional pulsed format, but many

new systems also use spread-

spectrum or frequency-chirped

and complex phase-coded pulse

confi gurations, which reveal more

precise data on the unknown target

returns.

Navigation systems such as the global

positioning system (GPS) use complex

phase-shift-keyed (PSK) formats to

yield precision radiolocation. Other

navigation systems use pulsed

formats for distance or coded target

identifi cation.

Some signals under test comprise of

multiple test tones and others contain

high harmonic content. Still others

are generated by frequency-agile

synthesizers, which can simulate

entire, full-channel communications

traffi c formats. These test signals

are used to characterize the real-

life performance of transmitters and

receivers such as satellite transponder

systems.

To test overload and rejection

characteristics of a receiver,

composites of out-of-channel

interference signals are created

for use as test signals. Whenever

such multiple signals are present,

composite carriers can add random

phases and create power “spikes”.

Thus, an application analysis is crucial

to understand these effects on the

power sensor.

In the sensor technology section

(Step 3), much more detail is given to

peak detection. Briefl y, the measuring

principle is that an averaging sensor

responds to the average value of

any format as long as the signal

peaks remain within the sensor’s

square-law range. But driving

ordinary diode sensors into their

linear-detection ranges, even those

with compensation techniques, will

cause errors. Peak and average diode

detectors, specifi cally designed for

peak excursions, generally do not have

problems with any type of complex

signal format.

4

Pulsed formats

Some modern radars used narrower

pulses that permitted better separation

resolution of multiple targets. Their

rise/fall times were proportionately

shortened as well, and the bandwidth

of the radar receiver increased. Then

came other technologies for pulsing

with longer phase-coded formats,

which made it possible to determine

factors such as the shape or size of

a target. Multiple pulses and random

pulse-repetition times are design

strategies needed for resistance to

countermeasures jamming.

All of these trends in pulse technology

mean that specifying a measurement

power meter requires a clear

knowledge of the key parameters that

need to be characterized. For some

test sequences, measurement of

the numerous pulse power and time

parameters performed by peak power

analyzers may be needed. On others,

the pulse top and average power will

suffi ce.

Design and production tests for pulsed

systems often require measurements

of both peak pulse power (pulse

top) as well as average power for

the transmitter and other system

components. Thermal sensors

inherently respond to total average

power, as long as the peak power

excursions do not exceed the peak

ratings of the sensor. And given a

pulsed waveform with a fi xed duty

cycle (pulse width/total pulse period),

its peak power can also be computed

using the average power from a

thermal sensor.

Diode-based sensors and associated

power meters, which are designed

for peak detection, are ideal when

the pulse-top characterization is

required, or when the pulse envelope

must be profi led. These peak sensors

feature wide-band amplifi cation of

the detected envelope, and permit

digital signal processing (DSP) to

measure and display the pulse shape

and numerical parameters. Most

modern radar and EW systems use

complex and pseudo-random pulse-

rate confi gurations for immunity to

jamming, and thus can’t use simple

computations based on duty cycle.

They require specifi c peak-type

sensors.

When measuring peak power, it is

important to understand the specifi c

test requirements for characterizing

the pulse parameters of a system or

component. For example, measuring

the rise time or fall time of a radar

pulse might be crucial for testing

the power amplifi er component. The

reason is that short rise/fall times

correlate with higher bandwidth of

the transmitted pulse and relate to

its ability to resolve targets. Yet, in

other production tests, perhaps on

later subsystems, it may only be

necessary to measure the pulse-top

power of the pulse. By knowing the

precise measurement specifi cation

required, a test engineer might use

a simpler and less expensive power

meter to determine that the subsystem

is operating within its proper

performance envelope.

Navigation systems such as air-traffi c

control (ATC) or distance-measuring

transceivers (DME) also have non-

traditional pulse confi gurations, such

as pulse pairs or triplets. In that case,

peak-detecting power meter/sensor

combinations are appropriate, such

as the Agilent E4416/17A meters

and E9320A sensors as well as

P-Series power meter N1911/12A and

wideband power sensor N1921/22A.

AM/FM formats

Not many systems are active these

days that are pure AM or FM, other

than commercial broadcast, and

perhaps amateur radio or “shortwave”

formats. Frequency modulation, since

its carrier amplitudes are relatively

constant, can be measured with

simple averaging power sensors.

Amplitude modulation signals, on

the other hand, must be analyzed

to ensure that the peak modulation

swings always remain below the limits

of the sensor’s “square-law” range,

since the modulation peaks result in a

(Vcarrier

)2 effect on power.

5

Digital and complex formats

Terrestrial communication

Terrestrial communication systems

abound with design examples of the

new digital phase modulation formats.

Some early migrations to microwave

terrestrial links from traditional FDM

(frequency-division-multiplex), used

64QAM (quadrature-amplitude-

modulation) formats.

Wireless and PCS

More recent wireless technologies

combined digital formats with

sophisticated carrier switching of

transmitted signals to permit time-

shared information from thousands of

mobile subscribers, who were arrayed

in cellular geographical regions.

Figure 1. The 3/8 shifted-8PSK digital

modulation format, emerging for use in

wideband data transmission on wireless

channels, as with EDGE technology.

TDMA (time division multiple

access) is the technology for time-

sharing of the same base station

channel. Encoded voice data and

new high-data-rate wireless links

are modulated unto the transmitted

carrier in the phase plane. These

create “constellations” of bit symbol

locations such as shown in the 3/8

shifted-8PSK confi guration shown in

Figure 1. This particular modulation

format is used in EDGE (Enhanced

Data Rates for GSM Evolution)

systems that offer high-data-rate

transfer over mobile wireless

channels. By packing 3 bits per

symbol, it increases data information

rates, but thereby increases amplitude

swings up to 16+ dB, making amplifi er

saturation more likely.

Each TDMA wireless subscriber’s

share of time might allow a useful

data burst of 524.6 µS, during which

it is crucial for the power amplifi er

to remain below its saturation

region. Driving the output stage into

non-linear amplifi cation causes the

outermost phase states to compress,

thereby increasing bit errors and

lowering system reliability.

Another competitive wireless

modulation technology is called code

division multiple access (CDMA),

which is used in IS-95 wireless

systems, among others. CDMA

encodes multiple data streams onto a

single carrier using a pseudo-random

code, with a resulting transmitted

power spectrum that exhibits almost

white-noise-like characteristics.

But, just like white noise, the average

power of the transmitted signal is

only one of the important parameters.

Because, statistically, multiple carrier

signal voltages can increase randomly,

instantaneous peak voltages can

approach ratios of 10 to 30 times the

rms voltage, depending on formats

and fi ltering. This ratio,calculated

with voltage parameters, is commonly

called crest factor, and is functionally

similar to a peak-to-average power

ratio that is measured by Agilent peak

and average power meters.1

System designers accommodate this

crest-factor effect by “backing off” the

power amplifi ers from their maximum

peak ratings to ensure that signal peak

power operation is always within their

linear range.

Accepted defi nition of crest factor (pulsed carrier): The ratio of the pulse peak (voltage) amplitude to the root-mean-square (voltage) amplitude1.

6

Two-tone and full-channel

formats

Intermodulation tests

Two-tone (or three-tone) test signals

often are used to characterize

amplifi ers for the linearity of their

amplifi cation. Amplifying two pure

input signals of f1and f2 results in

intermodulation signals at the output,

in the forms of 2f1– f2, 2f2 – f1, f1 ×

f2, and many more.

The measuring power of such

tones needs analysis because the

two carriers’ phases add or cancel

randomly over time. In a two-tone

example of V1 and V2, each with equal

power P, the constructive addition

of tones results in a peak carrier of

2 V that is a peak power of 4P. An

average-responding sensor would

indicate 2P, but a peak-responding

sensor would indicate 4P.

Noise-loading tests

Noise-loading tests of microwave

amplifi ers involve full-channel signals,

simulated by an input of white noise,

other than a single notched-out

(slot-fi lter) carrier. If there is non-

linear amplifi cation, the amount of

intermodulation power in the notch at

the output measures the performance

of the amplifi er.

There are also many examples of

simple CW signal testing. Metrology

laboratories provide typical

applications, such as power sensor

calibrators that are driven by CW test

signals. Many component tests use

simple unmodulated signals for test

procedures.

These above examples are intended to

illustrate that detailed knowledge of

your unknown signal and its spectrum

and modulation content is crucial

to your selection of the best power

sensor. In some cases, continuous

wave (CW) and averaging sensors

serve commendably. But other cases

require precise characterization of the

peak power performance to yield peak-

to-average power ratios or time-gated

parameters and ensure conformity to

specifi ed industry standards.

7

STEP 2

Understanding

Measurement

Uncertainties and

Traceability to National

Standards

The primary standard for an RF or

microwave power measurement is

a set of national power standards

maintained by the U.S. National

Institute of Standards and Technology

(NIST) in Boulder, Colorado, USA.

Many other countries also maintain

national power references and

regularly perform comparisons with

other standards laboratories in

sophisticated measurement-assurance

processes. These highly sophisticated

power standards are called

microcalorimeters (Figure 2) and are

the basic reference for measurement

services in coaxial and waveguide,

with transfer techniques capable of

achieving uncertainties of 0.42% at 18

GHz.

NIST and other national standards

agencies offer fee-based measurement

services for transferring such

standards to customer primary labs.

[1] [see reference literature]

They include comprehensive

documentation of the procedures,

with fee schedules and application

notes that provide detailed technical

descriptions of the theory and practice

of their measurement processes.

Agilent power instrumentation and

sensor calibrations are traceable to

those NIST standards, and to certain

other national standards. Agilent

performs its sensor production tests

using automatic network analyzers

for improved accuracy, by taking

into account the complex refl ection

coeffi cients of each individual

sensor. The sensors are furnished

with calibration charts that include

refl ection coeffi cient as well as

calibration factor data. With this

individualized test data, the user can

reduce measurement uncertainties

introduced by sensor-to-source

mismatch.

Figure 2. Schematic cross-section of the

NIST coaxial microcalorimeter at Boulder,

Colorado, U.S.A.

Measurement Uncertainty

Standards

In recent years, the world’s

metrology and quality community

has actively implemented a new

process for calculating and reporting

the uncertainties of measurement.

The process is based on a standard

promulgated by the International

Standards Organization, Geneva,

Switzerland, the ISO Guide to

the Expression of Uncertainty in

Measurement, often referred to as the

GUM.[2] [see reference literature]

NCSL International (previously the

National Conference of Standards

Laboratories) in Boulder, Colorado,

cooperating with the American

National Standards Institute, adopted

the ISO document as a U.S. National

Standard, and introduced it in the

USA as an industry document, ANSI/

NCSL Z540-2-1996, U.S. Guide to

the Expression of Uncertainty in

Measurement.[3] [see reference literature]

Both of the uncertainty standards

operate within a larger metrology

context, specifi ed by ISO Guide

25, General Requirements for the

Competence of Testing and Calibration

Laboratories. This document was

adapted for a U.S. version with

the identical title, ANSI/NCSL

Z540-1-1994.

Over the last several years, the ISO

has replaced ISO Guide 25 with

ISO/IEC 17025, and promulgated it

internationally. In the U.S., the ANSI/

NCSLI Standards Writing Committee

has recognized the advantage of a

worldwide standard and adopted the

ISO/IEC 17025 document as a U.S.

National Standard in cooperation

with the American Society of Testing

Materials (ASTM) and the American

Society of Quality (ASQ). To meet the

needs of users who rely on the older

ANSI/NCSL Z-540-1-1994 standard, it

has been offi cially extended for

fi ve years.

8

Measurement uncertainty standards

(continued)

Because of its international scope of

operations, Agilent Technologies has

moved quickly to adopt ISO/IEC 17025

in lieu of its previous commitment to

ANSI/NCSL Z-540-1. As a result, most

of Agilent’s production and support

operations are moving to offer optional

product-specifi c test data reports

compliant with 17025. Option 1A7

will ensure compliance with 17025

for new products shipped from the

factory and Agilent will provide for

support re-calibrations to the same

17025-compliant processes, data and

testing.,

The new processes provide more rigor

and standardization to the combined

uncertainties of power parameters,

from mismatching at measurement

and calibration time to the traceability

of the 50 MHz reference source.

An extended explanation of the

uncertainty calculation process

is detailed in Chapter 7 of Agilent

Application Note 64-1C Fundamentals

of RF and Microwave Power

Measurements, literature number

5965-6630E. In that example, 12

different uncertainty elements are

combined.

Readers who are embarking

on calculating measurement

uncertainties, should recognize that

the above-mentioned documents may

seem simple enough in concept, and

they are. But in the characterization

of more complex instrumentation, the

written specifi cation uncertainties

can often depend on multiple control

settings and interacting signal

conditions. Impedance bridges, for

example, measure using complex

number format. Network and

spectrum analyzers have multi-layered

specifi cations. Considerable attention

is being expended to defi ne and

characterize these extensions of the

basic GUM.

Generally, power measurement

uncertainties are relatively

straightforward. The dominant

measurement uncertainties include

sensor calibration factor uncertainty

and the mismatch between the source

under test and the sensor. For the

E-Series sensors, Agilent provides

temperature-banded calibration factor

uncertainties. The two temperature

bands are 25 ±10°C and 0 to 55°C.

These temperature ranges refl ect a

normal working environment (plus

a guard band) and the full specifi ed

operating temperature range.

The smaller calibration factor

uncertainties over 25 ±10°C are

therefore more realistic for R&D and

manufacturing environments, and

ultimately provide a lower overall

measurement uncertainty. Other

E-Series power sensor specifi cations

that provide temperature-banded data

are linearity and SWR.

Because the refl ection coeffi cient of

the test source is usually beyond the

control of the user, it is desirable to

choose power sensors with the lowest

specifi ed refl ection coeffi cient. Agilent

sensors are conservatively specifi ed,

and the actual refl ection coeffi cient

data for each sensor is furnished

with the sensor. If, for example, in

the sensor-specifi c calibration report,

the refl ection coeffi cient () value

was 0.01for a E9321A power sensor

(at 1 GHz), then the SWR would be

1.02 (Return Loss –40 dB). This value

could be used in the source/sensor

mismatch calculation, refer to Chapter

7, “Measurement Uncertainty,” in

Application Note Fundamentals of RF

and Microwave Power Measurements,

literature number 5965-6630E. This

SWR value would be in contrast

to the warranted maximum SWR

specifi cation of 1.12 (at ≤ 0 dBm, for 1

GHz) contained in Data Sheet E4416A/

E4417A EPM-P Series Power Meters

and E-Series E9320 Peak and Average

Power Sensor, literature number

5980-1469E. Like the temperature-

banded calibration factor data,

this value provides a lower overall

measurement uncertainty.

9

STEP 3

Understanding Agilent

Sensor Technologies and

Power Meter Features

In general, power sensors are

designed to match user signal formats

and modulation types. Similarly,

power meters are designed to

match the user’s measurement data

requirements. Sensor technology has

developed over the years to better

meet the advancing needs of users.

The thrust has been to increase

sensitivity and dynamic range, while

improving the speed, accuracy, and

reliability demanded by the fast-paced

industry.

Power sensors are of two general

types:

Heat-based 1. Diode-detector based2.

Heat-based sensors such as

thermistors and thermocouples

depend on the process of absorbing

all (except for tiny ineffi ciencies and

refl ections) of the RF and microwave

signal energy, and sensing the

resulting heat rise. Because the heat

effect integrates all the signal power,

such sensors are totally independent

of the waveforms and spectrum

content of the signal. Thus, they

respond to the true average power of

the signal, whether pulsed, CW, AM/

FM, or other complex modulation, and

account for spiked power effects such

as crest factor.

Diode-based sensors depend on the

rectifying characteristics of their

non-linear microwave detection

curve. Their ability to detect and

measure power down to -70 dBm suits

them for ultra-low signal detection

applications such as at the front end

of RF or microwave systems. They

are also ideal for wide-dynamic-range

measurements. Also, they provide

much faster response times, making

them important for pulsed and high-

data-rate applications.

While basic diode sensors operate

in their “square-law” range from –70

to –20 dBm, Agilent has extended

the diode technology into three other

areas, extended-range CW sensors,

two-path- diode-stack sensors for

higher power, and peak and average

sensors, which provide powerful

pulse-power characterization. All will

be described in this section.

Thermocouple technology

Agilent thermocouple sensors

use a heat-based design with

–30 dBm sensitivity and the high-

stability offered by a chopped-signal

amplifi cation path for the tiny DC

signal generated by the thermal

element. Agilent’s silicon-web

technology (circa 1974), which

absorbs the RF/microwave heat and

drives the silicon/metal thermocouple

element, provides a major advance

in improved impedance match (see

Figure 3). This results in lower

mismatch uncertainties and better

measurement confi dence. The chip

also features a rugged termination

design that withstands reasonable

signal overloads.

Typical modern thermocouple sensors

achieve wide frequency coverage

with coaxial inputs, but some are

confi gured in waveguides up to 50

GHz. With their dynamic power range

of –30 to +20 dBm, they measure

convenient ranges of system power

common in industry.

SiliconOxideSiO2

TantalumNitrideTa2N

Hot junction

WebDiffused

regionColdjunction

SiO2

Frame

SiO2

GoldAu

GoldAu

Figure 3. Cross section of Agilent thermocouple chip, where power

dissipated in the tantalum-nitride resistor heats the hot junction

10

Thermocouple technology (continued)

Thermocouple sensor accuracies

depend on a precise 50 MHz reference

power calibrator, which is resident in

each power meter. Used in conjunction

with an associated calibration factor,

the meter/sensor combination then

accurately transfers traceable power

references to all frequencies of the

sensor bandwidth.

Agilent has also extended the +20

dBm upper power range of several

families of coaxial thermocouple

sensors by including internal

attenuators for 3-watt and 25-watt

maximum inputs up to 18 GHz.

Conveniently, the attenuator

performance is included in the

calibration factor data for better total

accuracy.

The Agilent 8480A/B/H family

of sensors typify this powerful

thermocouple technology.

Thermocouple sensors are

recommended for all systems with CW,

pulsed-power or complex modulations,

because when the signal format lies

within their dynamic range, you can be

sure that the sensor is responding to

total aggregate (average) power.

For some tests, however, such as

a “mute” test on wireless power

amplifi ers (–55 dBm), limited

sensitivity requires a second sensor

to be used, increasing test times

in some applications. In addition,

measurements at the low-end of

the specifi ed range of thermocouple

sensors (typically –25 to –30 dBm)

sometimes require time-averaging to

produce an accurate, stable reading.

Diode technology

Diodes convert RF/microwave to DC

(or video in pulsed applications) by

means of their rectifi cation properties,

which arise from their non-linear

current-voltage characteristic. Figure

4 shows a typical diode detection

response curve starting near the noise

level of –70 dBm and extending up to

+20 dBm.

Figure 4. Diode detection characteristic:

square law from the noise level up to –20

dBm, followed by a transition region and

then a linear range to +20 dBm. Lower

graph shows deviation from “square-law.”

–70 –60 –50 –40 –30 –20 –10 0 +10 +20100nv

10v

1mv

100mv

10v

Det

ecte

d O

utpu

t –v

1v

100v

10mv

1v

Input Power -dBm

–60 –50 –40 –30 –20 –10 0 +10 +20–14

–10

–6

–2

+2

Dev

iatio

n fr

om S

quar

e La

w –

dB

–12

–8

–4

0

Input Power -dBm

In the lower “square-law”’ region,

the diode’s detected output voltage

is linearly proportional to the input

power (Vout proportional to Vin2)

and so responds linearly to power.

Above –20 dBm, the diode’s transfer

characteristic transitions toward

a linear detection function (Vout

proportional to Vin) , and the square-

law relationship is no longer valid.

Traditionally, diode power sensors

have been specifi ed to measure

power over the –70 to –20 dBm range,

making them the preferred sensor

type for applications that require

high-sensitivity measurements.

In applications that require fast

measurement speed, diode sensors

are chosen over thermocouple types

because of their quicker response to

changes of input power.

Diode sensors (Agilent’s 8480D-family)

average the effects of complex and

multiple signals within their square-

law range from –70 to –20 dBm,

providing that no peak energy can

exceed the –20 dBm level. This limits

their use considerably for pulsed-

power measurement. The diode

elements have also been designed

into waveguide sensors, with coverage

from 26.5 to110 GHz (8486-Series).

Extended dynamic-range diode

sensors

Agilent diode sensor technology now

permits measuring CW power over

an extended dynamic range from

–70 to +20 dBm, up to a frequency

range of 33 GHz. Their 90-dB range

makes them ideal for applications

with wide dynamic range, such

as high-attenuation component

measurements. When these sensors

are used with the EPM Series power

meters, they offer a fast measurement

speed mode: up to 200 readings/

second with the single channel

E4418B meter.

These E4412/13A sensors employ

a combination sensor-meter

architecture, whereby the calibration

factor is measured and stored in

an EEPROM within each individual

sensor and downloaded into the meter.

Because the correction factors are

derived from a CW source, they do not

provide an accurate average power

reading for modulated signals, such

as CDMA, when the signal peaks rise

above the diode’s square law region.

11

Two-path diode-stack sensors

When power testing from –70 dBm

up to +20 dBm is necessary, as has

become increasingly the case, the

traditional approach has been to

use a diode sensor to cover the low

range, and a thermocouple sensor

for the high end. In a high-volume

manufacturing environment, this

dual measurement confi guration

consumes too much test time,

especially if optimum accuracy must

be maintained.

The ideal averaging sensor would

combine the accuracy and linearity

of a thermal sensor with the wide

dynamic range of the extended diode

approach. Agilent’s E-Series sensors

based on a patented dual-path, diode-

attenuator-diode topology, have the

advantage of always maintaining one

of the two sets of sensing diodes

within their square-law region and

therefore responding correctly to

complex modulation formats.

The E-Series E9300 power sensors are

implemented as a Modifi ed Barrier

Integrated Diode (MBID). The MBID

comprises a two-diode-stack pair

for the low power path, a resistive

attenuator, and a fi ve-diode-stack pair

for the high power path, as shown in

Figure 5. Only one path is active at a

time, and switching between paths is

fast, automatic, and transparent to the

user, effectively producing an 80 dB

dynamic range over –60 to +44 dBm,

depending on the sensor model.

Lsense -

Lsense +

Hsense +

Hsense -

RF in

Figure 5. Simplified block diagram of the

two-path-diode-stack topology

This innovative approach has the

important application advantage

of enabling the sensor to handle

higher power levels without damage,

unlike simple diode sensors. This

is particularly useful with W-CDMA

signals, which exhibit high peak-to-

average ratios.

These MBID sensors have a maximum

average power specifi cation of +25

dBm and +33 dBm peak (<10 µS

duration). This means that the full

80 dB dynamic range can be used to

measure signals that simultaneously

have both high peak power and high

average power.

The new sensor technology facilitates

an inherently broadband technique for

measuring average power, without the

bandwidth or dynamic-range trade-offs

found with sampled techniques. These

sensors are an ideal fi t for users who

need the fl exibility to make wideband

average power measurements.

The E9300 family of sensors cover the

6 GHz and 18 GHz bands as shown in

the product listings of Table 7, page

24. Optional coverage for the 6 GHz

sensors extend to 18 GHz (Opt. H18

and H19), and for the 18 GHz products

to 24 GHz (Option H24 and H25).

Together with the new E-Series E9300

power sensors, the companion Agilent

EPM power meters (E4418B/19B) are

capable of accurately measuring the

average power of modulated signals

over a wide dynamic range, regardless

of signal bandwidth.

12

Peak and average power

sensors

(E9320 Series power sensors)

The Agilent E9320 peak and average

sensors presently cover the 50 MHz

to 6/18 GHz frequency ranges and

–65 to + 20 dBm power range. They

are optimized for comprehensive

measurements on pulsed envelopes

and signals with complex modulation.

When teamed with the new Agilent

EPM-P Series power meters (E4416A/

17A), they can handle test signal

envelopes with up to 5 MHz video2

bandwidth.

Of particular utility for production

testing, the meters’ 20 Msamples/

second continuous sample rate

permits fast measurement, via

the GPIB, of up to 1,000 corrected

readings per second, ideal for use in

automatic test system applications.

Agilent peak and average sensor/

meters feature two-mode operation:

normal for most average and peak

measurements (with or without time

gating), and average only for average

power measurements on low-level

or CW-only signals. Both modes use

the same micro-circuit diode-sensor

element.

The Agilent E9320 sensor family

(using the EPM-P meter) can provide

highly accurate and useful data for

parameters such as pulse top or

average power on pulses as narrow as

300 ns. While not specifi cally intended

for narrow pulse characterization, its 5

MHz bandwidth amplifi ers can deliver

the measurements shown in Table 1.

This capability is described further in

the power meter section on page 19.

Signal processing is provided by two

amplifi cation paths, each optimized

to its own data requirements. The

amplifi cation is distributed, with some

in the sensor unit and more in the

meter. In the average-only mode,

amplifi cation and chopping parameters

are much the same as in previous

Agilent diode sensors, with typical

dynamic power range of –65 to +20

dBm.

2. Note that the video bandwidth represents the ability of the power sensor and meter to follow

the power envelope of the input signal. The power envelope of the input signal is, in some

cases, determined by the signal’s modulation bandwidth, and hence video bandwidth is

sometimes referred to as modulation bandwidth.

13

Bandwidth considerations

In the normal mode, the separate-path

pulse amplifi er provides maximum

bandwidths of 300 kHz, 1.5 MHz or

5 MHz, defi ned by the sensor model

number. This allows the user to match

the test signal’s modulation bandwidth

to the sophisticated instrument data

processing. For example, the three

maximum bandwidth choices match

up with these typical wireless system

requirements:

300 kHz TDMA, GSM

1.5 MHz CDMA, IS-95

5 MHz W-CDMA, cdma2000

To further optimize the system’s

dynamic range, the video bandwidth

can be user-selected inside the meter

amplifi er to high, medium, and low, as

detailed in Table 2. Thus, when users

need to measure the power of multiple

signal types, within a single sensor,

by considering the dynamic range of

the bandwidth settings shown, they

can determine if they require only one

sensor or need multiple sensors for

their application(s).

With peak power measurements, it

is crucial to analyze the effect of the

instrumentation video bandwidths on

the accuracy of the resulting data.

Agilent E4416 /17A meters have

been optimized to avoid degrading

key specifi cations like linearity,

mismatch, dynamic range, and

temperature stability. For further

information on this matter, see the

article, “Power Measurements for the

Communications Market” [4] [see reference

literature]

Measurement accuracy is enhanced

without compromise, since the

sensors store their three-dimensional

calibration data in an EEPROM,

resident in each sensor. The data is

unique to each sensor and consists

of cal factor vs. frequency versus

power input versus temperature.

Upon power-up, or when the sensor

is connected, these calibration factors

are downloaded into the EPM-P Series

power meters.

(P-Series power sensors)

The Agilent N1921/22A P-Series peak

and average power sensors provide

wide-bandwidth power measurements

over a frequency range of 50 MHz

to 40 GHz with a dynamic range of

–35 dBm to +20 dBm. When used

together with P-Series power meters,

they provide up to 30 MHz video

bandwidth with 100 Msamples/ sec

of continuous sampling, optimized

for aerospace and defense, wireless

communication, and wireless

networking (IEEE 802.11a/b/g and

802.16e) applications. The fast

sampling rate permits the fastest

measurement speed among all Agilent

power sensors, via GPIB, with up to

1,500 corrected readings per second.

This rate optimizes production

throughput, while at the same time

improing the measurement accuracy.

The P-Series power sensors also have

built-in EEPROM to store calibration

factors and can download to power

meters automatically once connected.

They are also the fi rst Agilent power

sensors to provide “internal zero and

calibration” while the sensor is still

connected to device under test (DUT).

Key pulse parameter EPM-P/E9320 specifi cations

Rise time 200 ns

Fall time 200 ns

Minimum pulse width 300 ns

Pulse repetition rate 2 MHz

Pulse repetition interval 500 ns

Table 1. E9320-Series sensors measuring pulse parameters

Sensor model Modulation bandwidth/Max. dynamic range

6 GHz/18 GHz High Medium Low Off

E9321A/E9325A 300 kHz / –42 dBm

to +20 dBm

100 kHz / –43 dBm

to +20 dBm

30 kHz / –45 dBm

to +20 dBm

–40 dBm to +20 dBm

E9322A/E9326A 1.5 MHz / –37 dBm

to +20 dBm

300 kHz / –38 dBm

to +20 dBm

100 kHz / –39 dBm

to +20 dBm


E9323A/E9327A 5 MHz / –32 dBm

to +20 dBm

1.5 MHz / –34 dBm

to +20 dBm

30 kHz / –45 dBm

to +20 dBm


Table 2. E9320 sensor bandwidth versus peak power dynamic range (normal mode)

14

Internal zero and calibration

The P-Series power sensors (N1921A

and N1922A) provide internal zero and

calibration which eliminates the need

for sensor calibration using an external

reference source. The P-Series sensors

use Agilent’s patented technology (see

Figure 6) that integrates DC reference

sources and switching circuits into

each of the sensors. Thus, users can

zero and calibrate the sensors while

they are still connected to the device

under test. This feature removes the

need for connection and disconnection

from the calibration source, thereby

reducing test times, measurement

uncertainty, and wear and tear on

connectors. It is especially useful in

manufacturing and automated test

environments where every second and

every connection counts. Sensors can

now be embedded within test fi xtures

without the need to switch a 50 MHz

reference signal into the measurement

path, or to provide isolation from

signal sources for zeroing.

Thermistor technology

Agilent maintains a line of coaxial and

waveguide thermistor sensors and one

thermistor power meter. Thermistor

sensors are heat-based, and exploit a

balanced-bridge architecture using the

DC substitution method. Thus, they

are ideally suited for metrology-type

applications such as transferring a

reference power level from the primary

standards of a national laboratory,

or for an industry intercomparison

process called a Round Robin.

The Agilent 432A power meter and

associated 478/86 sensors and their

role in traceability processes is fully

detailed in Chapter 3 of Application

Note 64-1C, Fundamentals of RF and

Microwave Power Measurements,

literature number 5965-6630E. Custom

versions of the thermistor sensors,

which feature selected low-refl ection

coeffi cients, are available for the lower

uncertainties they provide to reference

power transfer applications.

Figure 6. Internal zero and CAL block diagram

15

Agilent power meters and USB

power sensor

Agilent offers power meters in six

basic families. (See Table 3.)

1. The P-Series N1911/12A

for peak and average power

measurements up to 30 MHz

video bandwidth. They have the

highest functionality, provide most

versatile measurements, and have

the fastest measurement speed

when used with the P-Series

power sensors. They are also

compatible with all Agilent diode

and thermocouple sensors.

2. The E4416/17A Series for peak

and average applications up to 5

MHz video bandwidth. They are

backward compatible with all

Agilent thermocouple and diode

power sensors.

3. The E4418/19B Series for

averaging power measurements.

They offer full capabilities for

average power applications, thus

utilizing all but the E9320- and

N1920-Series peak/average

sensors.

4. The E1416A (VXI) system power

meter is compatible with the 8480

Series sensors.

5. The 432A/478/486 thermistor

family, which is preferred for

metrology applications such as

reference power transfer.

6. The U2000 Series USB power

sensor for averaging power

measurement. They offer full

capability for average power

measurement without the need

for a separate power meter. This

is a cost-effective solution that

leverages the latest diode sensor

technology.

Agilent model Name Remarks

Peak and average power meter P-Series

N1911A Single-channel Digital, programmable, peak and average

measurements, uses N1921/22A sensors,

With built-in CCDF measurements.

Innovative time-gated pulse-power

measurement up to 30 MHz video

bandwidth. 100 Msamples/sec.

N1912A Dual-channel Two-channel version of N1911A, plus

measures and computes parameters

between the two sensors.

N8262A Dual-channel Modular power meter without front-panel

with two-channel version of N1911A,

plus measures and computes parameters


Peak and average power meters EPM-P Series

E4416A Single-channel Digital, programmable, peak and average

measurements, uses E9320 Series

sensors. Innovative timegated pulse-power

measurements. 20 Msamples/sec.

E4417A Dual-channel Two-channel version of E4416A, plus



Averaging power meters EPM Series

E4418B Single-channel Digital, programmable, uses E-Series and

8480 Series sensors, reads EEPROM-

stored sensor calibration factors of

E-Series sensors.

E4419B Dual-channel Two-channel version of E4418B, plus



System power meter

E1416A

VXI power meter Has functional performance features of

previous model 437B; uses all 8480-Series

sensors.

Thermistor power meter

432A Thermistor power

meter

DC-substitution, balanced-bridge

technology, ideal for reference power

transfers

Averaging power sensors U2000 Series

U2000A USB power sensor Digital programmable, average

measurement without power meter. USB

plug-and-play. Innovative time-gated pulse-

power measurement.

Table 3. Agilent’s family of power meters and USB power sensors

16

Peak and average meters

(P-Series power meters)

The P-Series power meters and

P-Series modular power meters

have 30 MHz video bandwidth

and a continuous sampling rate

of 100 M samples per second for

fast, accurate, and repeatable wide

bandwidth power, time, and statistical

measurements. When these meters

are used with the P-Series wideband

power sensors, they provide up

to 40 GHz of frequency coverage,

wide dynamic range, and extensive

measurement capability optimized

for aerospace and defense, wireless

communications, and wireless

networking (IEEE 802.11a/b/g and

802.16e) applications.

With a sampling rate of 100 M

samples per second, the P-Series

power meters and P-Series modular

power meters can capture single-

shot as well as repetitive events over

a wide bandwidth. For applications

such as radar and pulse component

testing that require accurate pulse

measurements, the power meter

and sensor combination has a 13

ns warranted rise and fall in time

specifi cations.

With up to 30 MHz of video bandwidth,

the P-Series also enables the single-

instrument solution for testing wide-

bandwidth products such as the multi-

carrier power amplifi ers used in a 3G

base station. The 30 MHz bandwidth is

corrected to 0.1 dB fl atness for highly

accurate peak power measurements.

Bandwidth considerations

The video bandwidths in the meter

can be set to High, Medium, Low,

or Off. The Off video bandwidth

setting provides the fastest rise and

fall time specifi cations. This is the

recommended setting for minimizing

overshoot on pulse signals. The high,

medium, and low settings are aimed

at measuring wide bandwidth and

modulated signals and are designed

to provide a fl at response across the

bandwidth. There are also trade-offs

between bandwidth and dynamic

range.

Figure 7 illustrates fl atness response.

The peak fl atness is the fl atness of a

peak-to-average ratio measurement for

various tone-separations for an equal

magnitude two-tone RF input. Figure

7 shows the relative error in peak-to-

average ratio measurements when the

tone separation is varied.

P-Series power meters and sensors

and P-Series modular power meters

offer comprehensive measurements

that satisfy the following requirements

of many power applications in R&D

and manufacturing.

1. Peak power, average power, and

peak-to-average ratio power

measurements

2. Time-gated and free-run

measurement modes

3. Automatic rise time, fall time,

pulse width, pulse period,

pulse repetition frequency,

time to positive and time to

negative transition occurrence

measurements

4. Complementary cumulative

distribution function (CCDF)

statistics

Parameter

Video bandwidth setting

Low: 5 MHzMedium: 15

MHzHigh: 30 MHz

Off

< 500 MHz > 500 MHz

Rise time/

fall time< 56 ns < 25 ns ≤ 13 ns < 36 ns ≤ 13 ns

Overshoot < 5% < 5%

Table 4. Dynamic response - rise time, fall time and overshoot, versus video bandwidth

settings

Figure 7. N192XA Error in peak-to-average measurements for a two-tone input (High,

Medium and Low or Off video bandwidth)

17

Versatile user interface

The P-Series power meters have

improved user interface and display

control. The color screen has a high-

resolution trace display size of 320 x

240 pixels in the large display mode.

This provides an attractive and clear

trace display.

A numerical keypad has also been

added. When combined with the

new stylized arrow keys and central

SELECT key, plus the standard hard

key/ soft key menu navigation, it helps

to provide an intuitive and convenient

user interface.

These interface features simplify the

confi guration of the meter for detailed

measurements. A Save/Recall menu

allows storage of up to ten instrument

confi gurations for easy switching of

test procedures.

The time-gated measurements are

similar to the EPM-P Series, where

up to four independent gates can be

setup to operate with different time

lengths and delays.

Each gate can measure the three

different parameters; average power,

peak power, or peak-to-average ratio.

These gate measurements can be

manipulated to compute combination

measurements, such as F1 – F2 or

F1/F2. This computational power is

important in wireless communications

where various computed parameters

are required.

Figure 8. Large color display with automatic power and time measurements

Figure 9. Measurement flexibility with four independent time gates

18

Flexible confi gurations

P-Series products come with fl exible

confi gurations. Users can choose

suitable confi gurations for their

desired applications.

P-Series power meters

N1911A single-channel power

meter, 9 kHz to 110 GHz

(sensor dependent)

N1912A dual-channel power

meter, 9 kHz to 110 GHz

(sensor dependent)

P-Series modular power meters

N8262A dual-channel power meter

9 kHz to 110 GHz

(sensor dependant)

P-Series power sensors

N1921A wideband peak and

average power sensor,

50 MHz to 18 GHz

N1922A wideband peak and

average power sensor,

50 MHz to 40 GHz

The P-Series power meters and

P-Series modular power meters are

also compatible with Agilent 8480,

E441x, and E9300 Series average

power sensors. This gives a selection

of more than 30 sensors for peak and

average power measurements over a

wide dynamic range from –70 to +44

dBm, with a frequency coverage of 9

kHz to 110 GHz.

Predefi ned measurement setups

P-Series power meters are loaded with time-saving features. Predefi ned test

setups for common measurements (see Figure 10) used in radar and wireless

communication applications allow easy meter setup for immediate testing.

The meter also has LAN, USB, and GPIB connectivity as a standard feature to

accommodate modern interfaces.

Measurements speed

When the P-Series power meters and sensors are used together, they provide

the fastest measurement speed of all Agilent power meters. The measurement

speed via remote interface is greater than 1,500 readings per second.

Measurement speed (readings/second)

Sensor type Normal X2 Fast

N192xA power sensors 1500

E9320 power

sensors

Average-only mode 20 40 400

Normal mode 20 40 1000

E441xA and E9300 power sensors 20 40 400

8480 Series power sensor 20 40 N/A

Table 5. Impressive GPIB measurement speed with P-Series power meters and sensors

Figure 10. Predefined test setups

19

P-Series soft front panel

The N8262A P-Series modular power

meter has performance equivalent

to that of the P-Series power meter

bench instrument. The Agilent N8262A

P-Series dual-channel modular power

meter is very slim (see Figure 11)

and supports LAN-based automated

measurements. It is an LXI (LAN

eXtensions for Instrumentation) Class-

C-compliant instrument that combines

the advantages of Ethernet with the

simplicity and familiarity of GPIB. This

helps the test system designers and

integrators to create faster and more

effi cient systems.

The N8262A P-Series modular power

meter comes with system-ready

software such as:

• Instrument page that provides

settings at a glance and enables

remote access/control. (see

Figure 12)

• User-familiar graphical user

interface that provides P-Series

N1911/12A front panel display

emulation (see Figure 13)

• IVI drivers used for test software

development that work with your

choice of programming languages

(Agilent VEE, LabView, Lab

Windows, C, C++, C#, VB and

Mathlab)

• Optional PC analysis software:

N1918A Power Analysis Manager

for complex pulse analysis,

statistical analysis, multi-channel

analysis, recording and playback

capability, and other features.

Figure 11. N8262A P-Series dual-channel modular power meter

Figure 12. N8262A P-Series dual-channel modular power meter insturment page

Figure 13. N8262A P-Series dual-channel modular power meter front panel display

20

EPM-P Series

The E4416/17A peak and average

power meters (EPM-P Series) are cost-

effi cient measurement tools for pulsed

and complex modulation formats. In

combination with the E9320 sensors,

they feature a user-friendly interface

and powerful display controls (See

Figure 14).

Hardkeys control the most frequently

used functions such as sensor

calibration and triggering, while

softkey menus simplify confi guring

the meter for detailed measurement

sequences. A Save/Recall menu

stores up to 10 instrument

confi gurations for easy switching

of test processes. In its GPIB

programming mode, it can output up to

1,000 corrected readings per second.

A large LCD display partitions up to

four-line formats to help interpret

and compare measurement results,

or presents large character readouts

to permit viewing from a distance.

For example, the four lines could be

confi gured to display average power in

dBm and mW, peak power, and peak-

to-average ratio. The user can also set

up a trace display as shown in

Figure 14.

Powerful digital signal processing

(DSP) mathematical processing

permits the meter to measure burst-

average and peak power, to compute

peak-to-average ratios, and display

other time-gated pulse power profi les

on the power meter’s large LCD

screen. The meters also measure

and display other complex wideband

modulation formats whose envelopes

contain high frequency components up

to 5 MHz.

For time-gated measurements,

the EPM-P Series meters excel in

versatility. The power meters measure

peak and average powers at user-

designated time gates and gate

widths along a test waveform. Figure

15 shows another typical time-gated

power measurement on a GSM signal.

Gate 2 provides the burst average

power over the “useful” GSM time

period, and Gate 1 indicates the peak

power over the complete timeslot.

Thus, a peak-to-average ratio

measurement can be obtained by

subtracting Gate 1 - Gate 2 (in dB).

Figure 14. E4417A power meter confi gured

to show a trace display (upper window)

and a dual numeric display (lower window)

This peak-to-average measurement

was made using two different gate

times and should not be confused

with the peak-to-average ratio

measurement in a single gate. A

pulse-drop measurement can be

obtained from the subtraction of the

two powers: Gate 3 – Gate 4. With the

four-line numeric display, all three of

these measurements can be displayed

simultaneously on the LCD screen,

along with the peak power from Gate

1.

All EPM-P Series power meters now

feature a fi rmware enhancement

for a graphical trace setup and

analysis screen. Figure 16 shows this

new feature with real-time marker

measurements on the meter’s trace

display. Markers 1 and 2 show the

instantaneous power and time

relative to a selected trigger event.

On the right side are computational

parameters of time, average, peak,

and peak-to-average power ratios

between markers 1 and 2. A trace-

zooming capability is also available for

more resolution on observations and

settings.

Figure 15. A GSM pulse, where powerful

data-configuration routines during four gate

times provide feeds for the display

Gate 3 Gate 4

Gate 2

Gate 1

Figure 16. Graphical display permitting marker-selected

power measurements, plus computations between the

marker-identified data

21

VEE analysis package

Perhaps even more important to

product-development and verifi cation

engineers is a powerful analysis

software package that totally controls

the EPM-P meter from the PC or

Laptop. This EPM-P VEE software

package is available free of charge. It

operates via the GPIB, and provides

the statistical, power, frequency, and

time measurements that are required

for CDMA and TDMA signal formats.

The CD-ROM package includes a VEE

installation program.

The statistical package includes the

ability to capture:

1. Cumulative Distribution Function

(CDF)

2. Complementary CDF (CCDF or

1-CDF)

3. Probability Density Function (PDF)

These are crucial diagnostic

parameters for system signals such

as CDMA formats. Figure 17 shows a

typical distribution function display.

Analyzing such power distribution

computations can reveal how a

power amplifi er may be distorting

a broadband signal that it is

transmitting. A baseband DSP signal

designer can completely specify the

power distribution characteristics

to the associated RF subsystem

designers.

Finally, the analysis package includes

a powerful pulse characterization

routine. It computes and displays the

following power parameters: pulse top,

pulse base, distal, mesial, proximal,

peak, average, peak/average ratio,

burst average, and duty cycle. It does

the same for these time and frequency

parameters: rise time, fall time, pulse

repetition frequency (PRF), pulse

repetition interval (PRI), pulse width,

and off time. All of these pulsed-power

parameters were originally defi ned

with the 1990 introduction of the

Agilent 8990A peak power analyzer.

Figure 17. Y-axis showing the percentage of time the signal power is at or

above the power specifi ed by the X-axis

22

N1918A Power Analysis

Manager

The N1918A Power Analysis Manager

is PC-based application software that

runs on the Microsoft® Windows®

platform and aims to enhance the

capabilities of some of Agilent’s power

meters and sensors. The N1918A

can interface with various hardware

devices, such as the N1911/12A

P-Series power meter, N8262A

P-Series modular power meter, and

U2000 Series USB power sensors.

The N1918A Power Analysis Manager

is a suite of software applications that

comprises the basic version (Power

Panel) and the advanced version

(Power Analyzer). The Power Panel

comes bundled with the purchase of

U2000 Series USB power sensors,

N1911/12A P-Series power meter,

and N8262A P-Series modular power

meter. The Power Panel offers an

easy-to-use standard GUI for the

hardware devices (see Figure 18).

The N1918A option 100, Power

Analyzer is an optional licensed

software solution that can be

purchased separately. The Power

Analyzer offers advanced functions

that include pulse analysis, multi-

channel power measurement,

statistical analysis, and recording. You

can use this software to perform tests

and measurements and track problems

at any stage of the design process,

from simulation to fi nal prototype (see

Figure 19).

Figure 19. Power Panel graphical user interface

Figure 20. N1918A Power Analyzer

23

Basic computation power

By confi guring the data obtained from the four gate periods, the E4416/17A

meters can present computed data on their large LCD displays. For example,

Figure 18 shows the data paths for the four independent gate periods. Each gate

can accumulate three different parameters; average, peak, or peak-to-average

ratio.

Each gate can then manipulate the selected parameter into two computed

parameters (F-feeds) per measurement channel (maximum), such as F1

minus F2 or F1/F2, to be displayed in one of the four window partitions. This

computational power is particularly valuable in TDMA scenarios such as GSM,

GPRS, EDGE, and NADC where various simultaneous combinations of computed

parameters are required.

This computational power is further enhanced in the E4417A dual-channel

power meter, which can add data feeds from its second sensor into the user-

confi gured display modes.

Gates 1 to 4 Measurement feeds(single or combined)

Display12

mea

sure

men

t hig

hway

Gate 1 Upper windowUpper measurement

Upper windowLower measurement

Lower windowUpper measurement

Lower windowLower measurement

Gate 2

Gate 3

Gate 4

Feed 1

Feed 2

Single

Feed 1 – Feed 2

Feed 1 / Feed 2

Combined

Feed 1

Feed 2

Single

Feed 1 – Feed 2

Feed 1 / Feed 2

Combined

Feed 1

Feed 2

Single

Feed 1 – Feed 2

Feed 1 / Feed 2

Combined

Feed 1

Feed 2

Single

Feed 1 – Feed 2

Feed 1 / Feed 2

Combined

PeakAveragePk-to-avg




Figure 21. User-confi gured data manipulations: a major feature of the EPM-P Series power meters.

System power meter

Agilent offers the E1416A VXI power

meter for system applications in the

industry-standard VXI confi guration.

The E1416A has the functional

performance and operating features of

the previous 437B power meter, except

that it has no front panel.

24

Averaging power meters

(EPM Series)

Average power meters respond to

all signals, whether CW, complex

modulation, or pulsed. The main

application criteria is whether the user

needs to characterize the modulation

or profi le the envelope of those

pulse parameters or simply requires

a measurement of average power.

In some cases of traditional pulsed

signals, where the duty cycle is known

and fi xed, system peak powers may

be computed from a knowledge of the

duty-cycle value and an average power

measurement.

The E4418/19B power meters and

E-Series sensor combination provides

measurement speeds of up to 200

readings per second over the GPIB

bus. The E-Series sensors cover a 90

dB power range from –70 to +44 dBm,

with frequency coverage to 26.5 GHz,

sensor dependent. For CW, multi-

tone, and modulation applications,

the E-Series sensors can make

measurements using only a single

sensor rather than several of the 8480

Series as before.

Agilent EPM Series meters operate

with the entire line of 8480 Series

thermocouple and diode sensors to

protect your equipment investment.

Programming code, written for the

previous 436A, 437B and 438A power

meters, is also directly usable with the

E4418B and E4419B power meters.

Average USB Power Sensor

(U2000 Series)

The U2000 Series USB average

power sensor offers USB base

connectivity via a PC plug-and-play

port for power measurement. With

the combined functionality of power

meter and power sensor, a U2000

Series power sensor returns the power

measurement readings and display on

your PC via a USB cable. The power

measurement reading can be retrieved

using the standard SCPI commands or

IVI.COM/IVI.C drivers. The feature-rich

N1918A Power Panel software that

comes with the purchase of the USB

power sensor allows you to monitor

the performance of the measurement

and perform data logging without

going through the programming guide.

The U2000 Series USB power sensor

provides measurement speeds up to

250 readings/sec over USB cable. The

USB sensor covers 80dB power range

from -60 to +20dBm, with frequency

coverage from 9KHz to 24GHz, sensor

dependent. The U2000 Series consists

of a built-in triggering circuit that

enables measurement synchronization

with the external instrument; even,

for example, to control the timing

of pulse-signal capture. For average

burst power measurement, the

U2000 Series USB power sensor can

perform the time-gated average burst

power measurement via its external

triggering capability.

Low current consumption

(approximately 170mA) enables a

number of U2000 Series USB power

sensors to be connected to a PC

without the need of external USB hub

to supply any additional power. No

external power supply is required to

power up the sensor because it uses

the power from the PC’s USB port.

25

STEP 4.

Comparing Performance

and Selecting the

Best Product for Your

Application

By far, most power measurements are

made with averaging power meters.

Based on the previous comparison of

sensor technology, and the selection

guide for sensors (see next page),

the user can easily determine which

sensor model meets the power and

frequency range performance required.

The compatibility table (Table 6) shows

which meters operate with which

sensors.

For averaging applications, the

two EPM power meters are prime

alternatives: Not only are they

designed for the E-Series CW and

E9300 sensors, but they are also

backwards-compatible with the

entire line of 8480 thermocouple and

diode sensors (but not thermistors).

Considering the large installed base of

Agilent sensors in most organizations,

this makes the EPM meters far more

versatile and cost effective. Further,

many calibration laboratories operate

with test systems which are designed

specifi cally to calibrate Agilent’s long

line of power sensors.

In spite of the popularity of averaging

meters, the rapid growth of the

wireless communications industry has

driven measurement requirements

into power characterizations of peak

power, peak burst, peak-to-average

ratio, burst average power, and other

important parameters. Agilent provides

three solutions for peak and average

power measurements: the N1911/12A

P-Series power meters, the N8262A

P-Series power meters, and the

E4416/17A EPM-P Series meters.

P-Series power meters and P-Series

modular power meters provide

innovative solutions to meet the

stringent needs of the industry.

These meters offer a wide bandwidth

peak power with up to 30 MHz video

bandwidth in your lab or on your

production line. They are Agilent’s

most versatile and fastest meters, with

a sampling rate of 100 Msamples per

second. They are designed for pulse

and radar component testing in the

aerospace and defense market, as well

as in wireless communication tests.

The Agilent EPM-P power meters are

a less costly solution for peak and

average power measurements of up

to 5 MHz video bandwidth with 20 M

Samples per second of continuous

sampling. They are optimized for

wireless communication tests.

In the benchtop or production line

environment, the choice is usually

between single- and dual-channel

capability. Agilent’s meters can sense

the specifi ed power range of the

individual sensor attached, and thus

ensure the correct power readout.

This feature also disables the readout

if the user applies too much power

and drives the meter outside the

specifi ed range, as with the standard

8480 Series diode sensors, which are

limited to a top level of –20 dBm.

In terms of GPIB programming

code, as well as complying with

the Standard Commands for

Programmable Instruments (SCPI),

the E4418B power meter has been

designed to be code-compatible with

the previous 436A and 437B. The

E4419B dua-channel power meter is

code-compatible with the previous

438A. This provides a substantial

saving in new programming costs. The

EPM Series power meters still offer

fl exibility, accuracy, and convenience

for manual applications in the research

lab.

For automated system use, the fast

measurement speed, (EPM–200

readings per second, EPM-P—1,000

readings per second, P-Series—1500

readings per second) make them ideal

for programmed applications. Their

digital-signal-processing (DSP) circuit

architecture not only provides for

powerful computation and averaging

routines, but also results in the

elimination of the standard range

switch-time delays, thus speeding up

the overall measurement.

Thermistor-based sensors and

meter for metrology applications

Finally, Agilent offers a line of coaxial

and waveguide thermistor sensors and

a full DC-substitution power meter,

the 432A, which serves metrology

applications for the transfer of power

standards.

26

Selection guides

Power measuring equipment for

all applications

Power measuring equipment is a key

part of Agilent’s instrumentation line

of RF and microwave measurement

tools. Through the decades, the

power-meter line has advanced by

adding the power of the newest

sensor technology and harnessing

the power of the microprocessor for

more capable and fl exible power meter

products.

From the original drift-prone thermistor

sensors of the 1950s, to low-SWR

thermocouple sensors, Agilent has

exploited the latest technologies to

take the inaccuracies out of your

power measurements. The latest

sensor technologies that use planar-

doped-barrier diodes in various

confi gurations now offer the best

in sensitivity and low drift for both

average-power and peak-power

measurements. And Agilent's newest

P-Series power meters and sensors

give you improved speed and accuracy

for measurements over a dynamic

range of –70 to +44 dBm, with sensor-

dependent, auto zero, and calibration

capability.

The latest technology of Agilent power

sensor, U2000 Series USB power

sensor, allows power measurement on

a PC via plug-and-play USB port and

without the need for a separate power

meter.

Table 6 presents a compatibility

overview of the entire Agilent power

measurement family, including meters

and sensors.

Agilent power meters

Agilent power

sensors

P-Series

peak,

average,

and time

gating

N1911A

single Ch

N1912A

dual Ch

EPM-P

Series

peak,

average,

and time

gating

E4416A

single Ch

E4417A

dual Ch

EPM

Series

averaging

E4418B

single Ch

E4419B

dual Ch

System

power

meter

Thermistor

power

meter

432A

P-Series

modular

peak,

average,

and time

gating

N8262A

dual Ch

Thermocouple

8480A/B/H-

family R/

Q8486A W/G

(11 models)

• • • • •

Diode

8480D-family

8486A/D-W/

G-family (7

models)

• • • • •

Diode sensors

with extended

range

E4421A/13A (2

models)

• • • •

Two-path-

diode-stack

E9300A family

(7 models)

• • • •

Peak and

average

sensors, E9320

family (6

models)

• • •

Thermistor

sensors 478

coaxial 486

waveguide (6

models)

•

Peak and

average

sensors

N1921/22A (2

models)

• •

Two-path-

diode-stack

U2000-family (4

models)

<power measurement without separate power meter>

Table 6. Agilent power meter/sensor compatibility chart

27

Agilent's family of versatile sensors

Table 7. Agilent's family of power sensors

Thermocouple sensors

25 W, 0 to +44 dBm

3 W, -10 to +35 dBm

100 mW, -30 to +20 dBm

8482B

8482H

8481B

8481H

8481A

8483A .75

8485AOpt 33

W/G

8487A

Q8486A

Frequency100 kHz 10 MHz 50 100 500 MHz 1 GHz 2 4.2 18.0 26.5 33 40 50 75 110 GHz

8482A

W/G

Sensor family

8480 series

Technology

Thermocouple

Max. dynamic range

50 dB

Frequency range1

100 kHz to 50 GHz

Power range1 Signal type Max. measurementspeed (rdgs/sec)

-30 to +44 dBm All signal types,unlimited bandwidth

40 (x2 mode)

R8486A

Thermocouple sensors

100 mW, -70 to +20 dBm


E4412A

E4413A

Sensor family

E-series: CWE4412AE4413A

Technology

Single diode pair

Max. dynamic range

90 dB

Frequency range1

10 MHz to 26.5 GHz


-70 to +20 dBm CW only 200 (fast mode)

100 mW, -70 to +20 dBm

Extended dynamicrange diode sensors

Opt H33

Extended-range diode sensors

1. Sensor dependant

Diode sensors

10 μW, -70 to -20 dBm


8481D8485D

Opt 33

8487D

R8486DQ8486D

W8486A

-30 to +20dBmW/G

W/GW/G

-30 to+20dBm

V8486AW/G

Sensor family

8480 series

Technology

Diode

Max. dynamic range

50 dB

Frequency range1

10 MHz to 110 GHz


-70 to -20 dBm All signal types,unlimited bandwidth

40 (x2 mode)

Diode sensors

28

1. Sensor dependant

100 mW, -60 to +20 dBm

Frequency

9 kHz 100 kHz 10 50 MHz 100 MHz 500 1 GHz 6 18.0 26.5 33 40 50 GHz

E9300A

E9301A

Sensor family

E-series: average powersensors E9300

Technology

Diode-attenuator-diode

Max. dynamic range

80 dB

Frequency range1

9 kHz to 18 GHz


-60 to +44 dBm All signal typesunlimited bandwidth

200 (fast mode)

100 mW, -60 to +20 dBm

Two path diode stack sensors

25 W, -30 to +44 dBm

25 W, -30 to +44 dBm

1 W, -50 to +30 dBm

1 W, -50 to +30 dBm

100 mW, -60 to +20 dBm

1 MHz

E9304A

E9300H

E9301H

E9300B

E9301B

24.0

Opt H24

Opt H18

1 W, -50 to +30 dBm

1 W, -50 to +30 dBm

E9300A Opt H25

E9304A Opt H19

Two-path diode stack sensors

Sensor family TechnologyMax. dynamic

range

Frequency

range 1 Power range 1 Signal typeMax. measurement

speed (rdgs/sec)

U2000-series

average power

sensors

U2000/01/02/04A

Diode-attenuator-

diode, two-path80 dB

9 kHz to

24 GHz

–60 to +20

dBm

All signal types,

unlimited

bandwidth

250 (fast mode)

100 mW, –60 to +20 dBm

100 kHz 1 MHz 10 50 MHz 500 1 GHz 6 18.0 24 33 40 GHz9 kHz

Frequency

100 MHz

U2000A

U2001A

U2004A

U2002A

U2000-Series average power sensor

29

100 mW, Avg. only: –65/60/60 to +20 dBm Normal –50/45/40 to +20 dBm

100 mW, Avg. only: –65/60/60 to +20 dBm Normal –50/45/40 to +20 dBm

Frequency

100 kHz 10 50 MHz 100 MHz 500 1 GHz 6 18.0 26.5 33 40 50 GHz

E9321A 300 kHz

E9322A 1.5 MHz

Sensor family

E9320-series2

peak and averageE9321/22/23AE9325/26/27A

Technology

Single diodepair, two-path

Max. dynamic range

85 dB

Frequency range1

50 MHz to 18 GHz


–65 to +20 dBm CW, avg, peak Up to 1000

1 MHz

E9323A 5 MHz

E9325A 300 kHz

E9326A 1.5 MHz

E9327A 5 MHz

Peak and average sensors (up to 5 MHz video bandwidth)

100 mW, –35 to +20 dBm

Frequency

100 kHz 10 50 MHz 100 MHz 500 1 GHz 6 18.0 26.5 33 40 50 GHz

N1921A 30 MHz

N1922A 30 MHz

Sensor family

N1921/22APeak and average sensors

Technology

Single diode pair, built in voltage reference for internal zero and calibration

Max. dynamic range

55 dB

Frequency range

50 MHz to 40 GHz

Power range Signal type Max. measurementspeed (rdgs/sec)

–35 to +20 dBm CW, avg, peak, pk/avg, TDMA, W-CDMA, radar

Up to 1500

1 MHz

Peak and average sensors (up to 30 MHz video bandwidth)

Sensor dependant1.

Peak and average sensors must be used with an E9288A, B, or C sensor cable, and only operate with the E4416A/17A power meters2.

30

References

[1] A Calibration Service for

Coaxial Reference Standards for

Microwave Power, Claque F.R.,

NIST Technical Note 1374, NIST,

325 Broadway, Boulder,

Colorado, USA, May 1995

[2] International Organization

for Standardization, Geneva

Switzerland, ISBN 92-67-10188-9,

1995

[3] National Conference of Standards

Laboratories, Boulder, CO, ANSI/

NCSL Z540-2-1996

[4] Anderson, Alan, Power

Measurements for the

Communications Market, MW/RF

Magazine, October 2000

For more information:

• Choosing the Right Power Meter

and Sensor, Product Note,

literature number 5968-7150E

• Fundamentals of RF and

Microwave Power Measurements,

Application Note 64-1C, literature

number 5965-6630E

Related Agilent literature

• EPM-P Power Meters and the

E9320 Series Power Sensors,

Technical Specifi cation, literature

number 5980-1469E

• EPM and EPM-P Series Power

Meters and E-Series Power

Sensors, Confi guration Guide,


• EMP-P Series Single and Dual-

Channel Power Meter-E9320

Family of Peak and Average

Power Sensors, Product Overview,


• EPM Series Power Meters,

E-Series and 8480 Series Power

Sensors, Technical Specifi cations,


• EPM Series Power Meters,

Product Overview, literature

number 5965-6380E

• E9300 Power Sensors, Product

Overview, literature number

5968-4960E

• CD-ROM: EPM and EPM-P Series

Power Meters, part number

E4416-90032

This CD-ROM contains the power

meters and sensors Learnware

(User’s Guides, Programming Guides,

Operating Guides and Service

Manuals). The CD-ROM also contains

technical specifi cations, data sheets,

product overviews, confi guration

guide, application and product notes

as well as power meter tutorials,

analyzer software for the EPM-P

power meters, IVI-COM drivers,

IntuiLink toolbar for the EPM power

meters and VXI Plug & Play drivers for

the EPM power meters.

This versatile CD-ROM package is

shipped free with every EPM and

EPM-P power meter.

Additional information is also available

at:

www.agilent.com

www.agilent.com/fi nd/emailupdates

Get the latest information on the

products and applications you select.

www.agilent.com/fi nd/agilentdirect

Quickly choose and use your test

equipment solutions with confi dence.

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open connectivity for a broad range

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You will always have the utmost

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For more information on repair and

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Printed in USA, June 4, 2008

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